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People are more willing to reward collaborators and punish lone
wolves in an effort to force cooperation in times of conflict,
according to the research, which was conducted during the 34-day
Israel-Hezbollah war in 2006. It's the first time that scientists
have tested the influence of real-world conflict on people's
cooperative
behaviors, said study researcher Daniel Fessler, an
anthropologist at the University of California, Los Angeles.

And while researchers can't be sure what the study participants
were thinking during the experiment, the results make sense from
an evolutionary perspective, Fessler said.

"The hypothesis is that whether through biological evolution,
cultural evolution or a combination of these, human psychology is
such that when the group is under attack, people increase the
importance they place on cooperation within the group," Fessler
told LiveScience. "They are more willing to sacrifice in order to
force others to be cooperative." [ Fight,
Fight, Fight: The History of Human Aggression ]

From terrorism to war

The study, published today (June 7) in the journal Proceedings of
the Royal Society B, was originally meant to tease out the
effects of terrorist attacks on cooperation. Study researcher
Ayelet Gneezy, a marketing professor at the University of
California, San Diego, had completed a few experiments in Tel
Aviv about nine months before the Israel-Hezbollah war. Gneezy
planned to wait for a terrorist attack to occur in Israel and
then run the same experiments again to compare the results.
Instead, a war broke out.

So Gneezy changed her focus to a new question: Would a not-so-distant
war influence her participants' cooperative behavior? She
went back to the Tel Aviv retirement community where she first
ran the experiments and recruited new volunteers. As the
participants were senior citizens, they were not in danger of
being called up for military service.

The participants were paired off to play one of two games, the
Trust Game or the Ultimatum Game. In the Ultimatum Game, one
player gets a pot of money and is told to divide it between
himself and a second player. If Player 2 deems the division fair
and accepts, the players get to divide and keep the money as
Player 1 decreed. If Player 2 thinks Player 1 is being unfair,
she can reject the offer, in which case both players get nothing.
Player 2 has to take a hit for making this decision, as she loses
out on whatever money Player 1 wanted to give, but at a certain
point, Fessler said, people would rather
punish the ungenerous partner than walk away with a paltry
sum of cash.

In the Trust Game, Player 1 gets some cash and can decide how
much to give to Player 2. Both players know that the cash Player
1 chooses to transfer will be tripled. Next, Player 2 gets to
make a decision about how much of the tripled cash to return to
Player 1. If they're a cooperative pair, Player 1 will transfer
all the money and Player 2 will transfer half back, ensuring they
both end up with 150 percent of what they started with. Player
2's willingness to transfer money back to Player 1 is a measure
of how much Player 2 is willing to give up to reward Player 1's
cooperative behavior.

War and cooperation

The researchers found that nine months before the war and one
year after the war, people showed similar levels of
cooperativeness when playing these games. But as the war raged,
the participants became much more willing to give up some of
their own cash to punish an uncooperative partner or reward a
cooperative one.

"The big finding is that war has a substantial effect on the
price that people are willing to pay to
enhance cooperation," Fessler said.

In the Ultimatum Game, for example, about 12 percent of Player 2s
rejected an offer of a 30-70 split with Player 1 as unfair during
peacetime. During wartime, that number rose to 40 percent. The
finding illustrates a greater willingness to give up cash to
punish an uncooperative player during war, Fessler said.

In a peacetime Trust Game, Player 2s sent back about the same
proportion of money to Player 1s regardless of how stingy Player
1 was with the transfer, Gneezy and Fessler found. But during
wartime, people responded strongly to Player 1's generosity (or
lack thereof). An initial transfer of a few dollars resulted in
only about a 25-percent return rate, while a transfer of the full
$50 inspired Player 2s to send 150 percent of the original (now
tripled) sum back.

Cooperation or rule-following?

Though it's not surprising that people might come together during
war time, the key finding is that people are willing to give up
their own resources to make that happen, Fessler said. Without
rewards and punishments, he added, cooperation fades over time.

The Israel-Hezbollah war was a short one, lasting barely a month,
so researchers aren't sure how people would react in a longer
conflict. No one has shown any effects of cooperation from the
Iraq and Afghanistan wars on U.S. citizens, Fessler said, which
may be because the wars are distant and civilians don't feel
unsafe.

The question now, Fessler said, is whether wartime has a specific
effect on cooperation or whether people just become
more moralistic and rules-driven in general.

"It could be either," Fessler said. "The next step is to see
whether these effects are exclusive to punishing and rewarding in
the context of cooperation or whether they are about enforcing
conformity to the rules more generally."